First let me say this is a great picture! I think if this picture would have been in a regular challenge and not a challenge with 800+ you probably would have finished in the top 25 if not better. Many people get tired after voting a while and start giving 4's and 5's.
Anyway, back to the picture. The best thing about the shot is the awesome sunset. The clouds give such a great feel to the picture. The sunset reflecting off the lake adds another pop to the picture. I also like how your mountain tops are different sizes. It really moves my eyes up and down, which I think is good.
The only thing I can find wrong with the picture is the lighting. Maybe a little bit more light may have helped. I think you lose detail when the picture is a little bit dark. Just my opinion.